tipc: merge link->exec_mode and link->state into one FSM
Until now, we have been handling link failover and synchronization
by using an additional link state variable, "exec_mode". This variable
is not independent of the link FSM state, something causing a risk of
inconsistencies, apart from the fact that it clutters the code.
The conditions are now in place to define a new link FSM that covers
all existing use cases, including failover and synchronization, and
eliminate the "exec_mode" field altogether. The FSM must also support
non-atomic resetting of links, which will be introduced later.
The new link FSM is shown below, with 7 states and 8 events.
Only events leading to state change are shown as edges.
+------------------------------------+
|RESET_EVT |
| |
| +--------------+
| +-----------------| SYNCHING |-----------------+
| |FAILURE_EVT +--------------+ PEER_RESET_EVT|
| | A | |
| | | | |
| | | | |
| | |SYNCH_ |SYNCH_ |
| | |BEGIN_EVT |END_EVT |
| | | | |
| V | V V
| +-------------+ +--------------+ +------------+
| | RESETTING |<---------| ESTABLISHED |--------->| PEER_RESET |
| +-------------+ FAILURE_ +--------------+ PEER_ +------------+
| | EVT | A RESET_EVT |
| | | | |
| | | | |
| | +--------------+ | |
| RESET_EVT| |RESET_EVT |ESTABLISH_EVT |
| | | | |
| | | | |
| V V | |
| +-------------+ +--------------+ RESET_EVT|
+--->| RESET |--------->| ESTABLISHING |<----------------+
+-------------+ PEER_ +--------------+
| A RESET_EVT |
| | |
| | |
|FAILOVER_ |FAILOVER_ |FAILOVER_
|BEGIN_EVT |END_EVT |BEGIN_EVT
| | |
V | |
+-------------+ |
| FAILINGOVER |<----------------+
+-------------+
These changes are fully backwards compatible.
Tested-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/node.c b/net/tipc/node.c
index 9e20acf..a3ceeda 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -334,7 +334,6 @@
if (!ol) {
*slot0 = bearer_id;
*slot1 = bearer_id;
- nl->exec_mode = TIPC_LINK_OPEN;
tipc_link_build_bcast_sync_msg(nl, xmitq);
node_established_contact(n);
return;
@@ -368,7 +367,7 @@
struct sk_buff_head xmitq;
l = n->links[bearer_id].link;
- if (!l || !tipc_link_is_up(l))
+ if (!l || tipc_link_is_reset(l))
return;
__skb_queue_head_init(&xmitq);
@@ -414,6 +413,7 @@
n->sync_point = tnl->rcv_nxt + (U16_MAX / 2 - 1);
tipc_link_tnl_prepare(l, tnl, FAILOVER_MSG, &xmitq);
tipc_link_reset(l);
+ tipc_link_fsm_evt(l, LINK_FAILOVER_BEGIN_EVT);
tipc_bearer_xmit(n->net, tnl->bearer_id, &xmitq, maddr);
}
@@ -749,7 +749,7 @@
struct tipc_link *l_ptr = n_ptr->links[i].link;
if (!l_ptr)
continue;
- l_ptr->exec_mode = TIPC_LINK_OPEN;
+ tipc_link_fsm_evt(l_ptr, LINK_FAILOVER_END_EVT);
kfree_skb(l_ptr->failover_reasm_skb);
l_ptr->failover_reasm_skb = NULL;
tipc_link_reset_fragments(l_ptr);
@@ -989,7 +989,7 @@
* Returns true if state is ok, otherwise consumes buffer and returns false
*/
static bool tipc_node_check_state(struct tipc_node *n, struct sk_buff *skb,
- int bearer_id)
+ int bearer_id, struct sk_buff_head *xmitq)
{
struct tipc_msg *hdr = buf_msg(skb);
int usr = msg_user(hdr);
@@ -1042,42 +1042,47 @@
/* Initiate or update failover mode if applicable */
if ((usr == TUNNEL_PROTOCOL) && (mtyp == FAILOVER_MSG)) {
syncpt = oseqno + exp_pkts - 1;
- if (pl && tipc_link_is_up(pl)) {
+ if (pl && tipc_link_is_up(pl))
tipc_node_link_down(n, pl->bearer_id);
- pl->exec_mode = TIPC_LINK_BLOCKED;
- }
+
/* If pkts arrive out of order, use lowest calculated syncpt */
if (less(syncpt, n->sync_point))
n->sync_point = syncpt;
}
/* Open parallel link when tunnel link reaches synch point */
- if ((n->state == NODE_FAILINGOVER) && (more(rcv_nxt, n->sync_point))) {
+ if ((n->state == NODE_FAILINGOVER) && !tipc_link_is_failingover(l)) {
+ if (!more(rcv_nxt, n->sync_point))
+ return true;
tipc_node_fsm_evt(n, NODE_FAILOVER_END_EVT);
if (pl)
- pl->exec_mode = TIPC_LINK_OPEN;
+ tipc_link_fsm_evt(pl, LINK_FAILOVER_END_EVT);
return true;
}
/* Initiate or update synch mode if applicable */
if ((usr == TUNNEL_PROTOCOL) && (mtyp == SYNCH_MSG)) {
syncpt = iseqno + exp_pkts - 1;
+ if (!tipc_link_is_up(l)) {
+ tipc_link_fsm_evt(l, LINK_ESTABLISH_EVT);
+ tipc_node_link_up(n, bearer_id, xmitq);
+ }
if (n->state == SELF_UP_PEER_UP) {
n->sync_point = syncpt;
+ tipc_link_fsm_evt(l, LINK_SYNCH_BEGIN_EVT);
tipc_node_fsm_evt(n, NODE_SYNCH_BEGIN_EVT);
}
- l->exec_mode = TIPC_LINK_TUNNEL;
if (less(syncpt, n->sync_point))
n->sync_point = syncpt;
}
/* Open tunnel link when parallel link reaches synch point */
- if ((n->state == NODE_SYNCHING) && (l->exec_mode == TIPC_LINK_TUNNEL)) {
+ if ((n->state == NODE_SYNCHING) && tipc_link_is_synching(l)) {
if (pl)
dlv_nxt = mod(pl->rcv_nxt - skb_queue_len(pl->inputq));
if (!pl || more(dlv_nxt, n->sync_point)) {
+ tipc_link_fsm_evt(l, LINK_SYNCH_END_EVT);
tipc_node_fsm_evt(n, NODE_SYNCH_END_EVT);
- l->exec_mode = TIPC_LINK_OPEN;
return true;
}
if ((usr == TUNNEL_PROTOCOL) && (mtyp == SYNCH_MSG))
@@ -1143,7 +1148,7 @@
tipc_bclink_acknowledge(n, msg_bcast_ack(hdr));
/* Check and if necessary update node state */
- if (likely(tipc_node_check_state(n, skb, bearer_id))) {
+ if (likely(tipc_node_check_state(n, skb, bearer_id, &xmitq))) {
rc = tipc_link_rcv(le->link, skb, &xmitq);
skb = NULL;
}